Re: Header unfolding in archived mail

On Sat, Sep 07, 2013 at 06:07:45PM -0400, Noah Misch wrote:
> The mailing list web archives display the subject of message
> 20130603190727.GA360354@tornado.leadboat.com as follows:
>
> Partitioning performance: cache stringToNode() ofpg_constraint.ccbin
>
> Note the lack of whitespace after "of".  The original message, which you can
> see by downloading the mbox for June 2013, conveyed the subject this way:
>
> Subject: Partitioning performance: cache stringToNode() of
>       pg_constraint.ccbin
>
> Per RFC 5322, section 2.2.3:
>
>    The process of moving from this folded multiple-line representation
>    of a header field to its single line representation is called
>    "unfolding".  Unfolding is accomplished by simply removing any CRLF
>    that is immediately followed by WSP.  Each header field should be
>    treated in its unfolded form for further syntactic and semantic
>    evaluation.  An unfolded header field has no length restriction and
>    therefore may be indeterminately long.
>
> So, the archives should present the subject like this:
>
> Partitioning performance: cache stringToNode() of     pg_constraint.ccbin
>
> Gmane and osdir.com do so.  MARC and Gmail show a space in place of the tab,
> but Gmail converts every subject-line tab to a space.  I have attached a
> patch, against pgarchives.git, making its unfolding code conform to RFC 5322.
> The change also affects headers folded before a space rather than before a
> tab, such as 50E31370.5030405@cybertec.at.  Those have been displaying fine
> despite the lack of unfolding because newline-space renders like a space in
> HTML.  I unit-tested the change, but I did not test the full archives load.
>
>
> The "raw" message display feature seems to have its own set of rules, and I
> failed to find their implementation.  Here are the subject lines for the
> aforementioned messages according to "raw" display:
>
> Subject: Partitioning performance: cache stringToNode() of pg_constraint.ccbin
> Subject: Review of "pg_basebackup and pg_receivexlog to use non-blocking socket
>       communication", was: Re: Re: [BUGS] BUG #7534: walreceiver takes
>       long time to detect n/w breakdown
>
> In one case, "\n\t" from the true raw original (in the mbox file) became " ".
> In the other case, two instances of "\n " became "\n\t".  Any ideas where that
> transformation is coming from?

Ping.  Any advice on how to more-thoroughly test the pgarchives.git change, or
where I might find the corresponding code affecting "raw" message display?